Optical Coherence Tomography (OCT) is a leading-edge imaging technology that is transforming medical diagnostics and research. It provides high-resolution cross-sectional images of biological tissues, enabling detailed analysis and visualization of structures, especially blood vessels.
The addition of Optical Coherence Tomography Angiography (OCTA) has further enhanced the precision and informativeness of blood vessel imaging. This article explores the key components and capabilities of OCT systems, their diverse applications, and their significant impact on diagnosing and managing diseases such as age-related macular degeneration (AMD) and macular edema.
At the heart of OCT is low-coherence interferometry. An OCT system includes essential components such as a light source, a beamsplitter, reference and sample arms, and a detection system.
The system emits light, usually in the near-infrared spectrum, which is then divided into optical and reference beams. The optical beam interacts with the tissue, creating interference patterns. These patterns are processed to reconstruct detailed cross-sectional images of the tissue.
Axial resolution is a critical factor in determining the quality of OCT images. It defines the system’s capability to distinguish between structures along the depth or axial direction. With resolutions reaching the micrometer range, OCT systems are adept at providing intricate visualizations of tissue layers and microstructures.
There are two main types of OCT systems: Time-Domain OCT (TD-OCT) and Spectral-Domain OCT (SD-OCT).
TD-OCT employs a moving reference mirror to enable depth scanning, while SD-OCT uses a spectrometer to enable simultaneous depth information capture, therefore improving signal-to-noise ratios and imaging speeds.
OCT technology has advanced to include a range of new features; for example, Polarization-Sensitive OCT (PS-OCT), which leverages the polarization properties of light to provide vital insight into tissue birefringence and structural characteristics.
This information allows users to effectively visualize nerve bundles, collagen fibers, and other polarizing tissue structures.
OCT Angiography (OCTA) is an extension of OCT that facilitates non-invasive blood vessel imaging. OCTA leverages the motion contrast of flowing blood cells, using this to generate en-face images of the vasculature without the need for contrasting agents.
By analyzing changes in the OCT signal over time, it is possible to create detailed maps of the vascular network, which are key to performing perfusion evaluations and identifying vascular abnormalities.
OCT has as a wide range of applications in various medical fields, particularly in ophthalmology, where it has revolutionized the diagnosis and management of retinal diseases such as AMD.
High-resolution images of the retina provided by OCT enable precise identification of drusen, retinal pigment epithelial detachments, and fluid accumulations, aiding in the timely diagnosis and ongoing monitoring of AMD.
The capabilities and uses of OCT are continually expanding, significantly enhancing our understanding and management of various medical conditions. For those interested in exploring how OCT can be integrated into their projects, a free consultation or a quote is available through Shanghai Optics’ contact page.
